Improvement in machines for making screws



- 2 Sheets-Sheet 1.

T. T. PROSSER.

Machine for Making Screws.

No. 58,134. Patented Sept. 1 1866'.

2 Sheets-Sheet 2.

T. T. PROSSER.

Machine for Making Screws.

' Patented Spt. 18.1866.

EITED- STATES,

TREAT T. PBOSSER, or CHICAGO, ILLINOIS, ASSIGNOR To HIMSELF, e. w.GILLETT, J. A. EASTMAN, 1). KIMBARK, JR, AND D. H. WELLS, or SAME PLACE.

IMPROVEMENT IN MACHINES FOR MAKING SCREWS.

Specification forming part of Letters Patent No. 58,134., datedSeptember 18, 1866.

To all whom it may concern:

Be it known that I, TREAT T. PROSSER, of the city of Chicago, in thecounty of (look and State of Illinois, have invented certain new anduseful Improvements in the IIIanufacture of Screws and Bolts; and I dohereby declare that the following is a full, clear, and exactdescription thereof, reference being had to the accompanying drawings,making part of this specification, and to the letters of referencemarked thereon, like letters indicating like parts wherever they occur.

- To enable others skilled in the art to construct and use theinvention, I will proceed to describe it.

My invention relates to the manufacture of metal screws, including boththose denominated wood-screws and bolts, anditconsists in forming thethread thereon by a process of rolling instead of cutting away a portionof the metal, as is usually done.

It also consists in the construction of a machine specially adapted tothis process, as hereinafter more fully explained.

Figure 1 is a side elevation of the machine. Fig. 2 is a topplan view ofthe same; and Figs. 3, 4, and 5 are views of portions of the machinedetached and more fully shown in detail.

It is customary to make screws by cutting the wire or rods into blanksof the proper length, and then form the thread by cutting away a portionof the metal, leaving that portion on which the thread is formed of thesame or less diameter than it was before the thread was out. By thuscutting the metal away to form the thread of the screw the longitudinalfibers of the metal are all cut off to the depth of the thread on thescrew. Consequently the screw is very much weakened, and both itstensile and torsional strength reduced thereby to about one-half of itsoriginal strength; whereas by my process I do not cut away any portionof the metal to form the thread of the screw; neither do I reduce itsstrength but slightly, if at all, but form the thread or threads on myscrews by a process of rolling or pressing of the blank between two setsor series of revolving roller dies or swages.

One set of dies or rollers being on each side of the blank and the anvilbeneath it, the rollers or dies in revolving seize the blank betweenthem and force it down onto the anvil or stationary die, and as therollers pass the blank indentations are made by them in the blank tocorrespond with the force of the rollers. Thus each pair of rollers inthe heads seizes the blank once at each revolution of the head, and asthe blank is revolved and thrown forward these indentations form thescrew. By thus rolling it into the required shape the thread portion ofthe screw is raised, thus making it or the thread portion of the screwof greater diameter than the Shank, and of nearly the same strength asthe shank-an important result that cannot be accomplished by the oldprocess of cutting away the metal to form the thread.

To make this style of screw I construct a machine consisting of a frame,A, of any suitable size and style, as represented in Figs. 1 and 2. Uponthis frame, at one end, is

' mounted a pair of parallel shafts, B, having spur-wheelsc applied atone end, and engaging one with the other for the purpose of causing thetwo shafts B to revolve with perfect uniformity, these shafts beingdriven by belts e and c from the driving-shaft J, (shown more clearly inFig. 2,) one of said belts being crossed to give the required motion'tothe shafts B and devices attached thereto. Upon the opposite ends ofthese shafts B are secured two circular heads, In each of these heads,between the flanges, a serieszo f hardened-steel rollers, a, are securedby a bolt 'or axis, S, upon which the rollers a revolve when they comein contact with the screw. The periphery of these rollers is providedwith circumferential grooves of the form andsize of the thread to beformed upon the screw that is intended to be made, these grooves formingrings around the rollers at right angles to the axis of the rollers.

In Fig. 3 is shown a longitudinal section of the circular heads 0 of thesteel roller-dies a, and of the axis S, taken through the line as w ofFig. 5 and in Fig. 5 the two heads 0, Steel roller-dies (1, axis S, andshafts B are represented in transverse section taken through or on theline y y of Fig. 2.

The hardened-steel rollers or dies a a. are shown in their workingposition on each side of the anvil or stationary swage w, and as theshafts B B revolve each pair of rollers or diesare carried forward andpass the anvil in the same relative manner.

It will be seen that the stationary anvil w has its upper surfacegrooved to correspond with the thread of the screw to be formed, whichconstitutes all of my swaging or rolling apparatus proper.

To feed the blank forward to the dies or rollers, and to hold and rotateit while the thread is being formed, I provide the shaft F, which has ahole bored longitudinally through it, and is so located that a blankforced through it will be delivered between. the revolving heads andseized by the cast steel roller-dies 'a a and forced down onto the anvilw. Upon the rear portion of this shaft F is cut-a screwthread, havingthe same inclination or pitch of thread asthat intended to be formed onthe screw-blank; and as this portion of the screw-shaft works in abearing having a corresponding female screw, the shaft is thus forcedforward when revolving one way and back when revolving in the oppositedirection. This shaft is driven by a friction-pulley, G, which is drivenby pulleys P and P, which latter are hung in an oscillating frame, sothat either of them may be brought into contact with the pulley G, asdesired, and as these pulleys revolve in opposite directions by means ofbelts a and a from the driving-shaft J, the shaft F is thereby made toadvance or recede with a speed proportional to its velocity of rotation.Upon the front end of this shaft F is secured a chuck, E, for holdingthe blank while the shaft F presents it for the action of the rollerswa-ges or dies, and withdrawing it therefrom.

The chuck consists of a disk, E, mounted loosely on the shaft F, and isrecessed on its face of proper depth to receive the arms 19 and permit aface-plate to be screwed over them, leaving the latter free to move inthe plane of the rotation of the disk.

The arms or jaws p are pivoted at their outer ends to the disk E, theirinner ends extending through openings formed in the sides of the shaft Fto the hole in said shaft, as shown in Fig. 4. Asprin g, b, is attachedto each of the arms 19, as shown in Fig. 4, the opposite end of thespring pressing upon the projection formed on the edge of the adjoiningjaw p, as shown, these springs thus tending to throw or press the jaws pinward toward the center until they rest against the solid portion 2; ofthe shaft. The inner ends of these jaws p are beveled or inclined, asshown, so that as they approach each other these inclined ends willgrasp and hold the blank that may be forced along the hole in the shaftF, and thus be brought between them, the pressure of the spring ttending to turn the disk E on the shaft F in the direction indicated bythe black arrow, by which the jaws p are closed and made to grasp andhold the blank tightly. To release the blank from the grasp of the j awsit is only necessary to turn the disk in the opposite direction, asindicated by the red arrow, by which thejaws will open.

H represents a hopper located directly in the rear of the shaft F, thesides of the hopper being inclined and terminating at the bottom in acavity of sufficient width to permit but a single blank to rest therein,the bottom being so arranged that the blank resting thereon shall beexactly opposite the hole in the rear end of the shaft F, there being anopening in both front and rear sides of the hopper at the bottom. At therear of the hopper is placed a sliding block or follower, I, the frontpart of which is of a size corresponding with the blank, and is arrangedto enter through the rear opening of the hopper, to push a blank forwardinto the open rear end of shaft F from the hopper, the spiral springs71. serving to draw the follower I forward for that purpose. On the rearend of the shaft F is a grooved collar, k, embracing a projection, I, ona sliding piece, w, which is located directly under the hopper, as shownin Fig. 1. At the rear end of this slide 20 is attached a cross-bar, T,which projects slightly on each side, and as the latter is forced backby the shaft F it presses against the end of a springbar, a, attached tothe front of the follower I, thereby shoving the latter back with it andcarrying the projecting point 2 out of the hopper, as shown in Fig. 1.

An incline, o, is located in such a position that when the follower Ihas been shoved back as far as required the spring-bar a will ride upthereon, and, being thus raised above, the cross-head T will be releasedfrom it, when the springs It will immediately draw the follower Iforward, causing the point z to push a blank forward from the hopperinto the shaft F.

A rock-shaft, d, is secured to the side of the frame opposite the chuckE. (See Figs. 1 and 2.) To this shaft d is attached an arm, f, whichprojects to such a distance that when turned down its end will comedirectly opposite the hole in the end of shaft F, a spiral spring, m,operating to keep the arm turned up. At the opposite end of this shaft dis secured aprojecting spring-arm, c, which, when the shaft F is movedentirely back, is struck by the pin 1' protruding from the rear face ofdisk E. As the shaft F begins its forward movement the pin 1, strikingagainst the arm 0, turns the rock-shaft d, thereby swinging the arm fdown in front of the opening in the shaft F, the disk E, by the pressureof arms 0 against the pin 1 being at the same time turned so as to openthe jaws p and thus release the screw previously formed, the pressure ofthe follower I at the same time forcing another blank out at the frontend of the shaft F until it strikes the arm f, the pin i having at thesameinstant slipped past the arm 0, thereby simultaneously permittingthe jaws p to grasp the blank and the arm f to fly up out of the way, sothat the blank can be carried forward between the swages or rollers a a.

From this description it will be seen that it is only necessary to fillthe hopper H with the blanks and start the machine, a sufficient numberof the blanks having previously been placed in the hollow of the shaft Fto fill it. and one having been suitably arranged in the chuck, afterwhich the operation of the machine becomes automatic.

As the blank is carried forward it rests upon the anvil u, and is struckand pressed by the rolls a, which are constantly and rapidly revolving,thereby raising the thread on the blank. As the motion of the shaft F isre versed, and the screw thus formed is drawn back, the rolls a stillcontinue to revolve, and thereby serve to smooth and more perfectlyfinish the thread.

Having thus described my invention, what- I claim is-- 1. The method offorming the threads on screws by means of revolving swages or dies, I

arms f and 0, when arranged to operate as and for the purposes setforth.

6. In combination with the shaft F and hopper H, the follower I,arranged to operate as described, for the purpose of feeding the blanksinto the shaft F, as set forth.

' TREAT T. PROSSER.

Witnesses P. T. DODGE, W. 0. DODGE.

